Apple and its business partners began taking orders on Friday for its iPhone 5C, the lower-end of two smartphone models introduced earlier this week, but not without some hiccups.

Preorders were set to begin at 12:01 a.m. Friday, but Apple's online stores weren't usable until 12:12 a.m. Customers might have had better luck with T-Mobile in Germany and O2 in the United Kingdom, which began presales just after midnight PT.

In the United States, the online stores of AT&T and T-Mobile were taking orders, too, though Sprint and Verizon Wireless still showed only information pages at 12:20 a.m., but by 12:56 a.m., they both had begun selling the new iPhones, too.

With five colors to choose from, as well as 16GB and 32GB models, inventory management becomes more complex in the iPhone 5C era. Sprint said it would ship iPhone 5C models within two weeks -- except for yellow ones, which would ship within three weeks.

By 1 a.m., Apple's stores in the U.K., France, Germany all showed delivery dates of September 20, indicating that demand has yet to outstrip the initial supply of phones.

The iPhone 5C, whose internals are very similar to those of the now-discontinued iPhone 5 that arrived last year, costs $99 for the 16GB version and $199 for 32GB with a two-year contract. Customers can place orders online now, but the phones won't be delivered until September 20, when the phones also will go on sale in stores.

Apple isn't offering a preorder option for the iPhone 5S, its new high-end model that starts at $199 and adds new hardware features like a faster A7 processor, fingerprint security system, improved camera, and a speedier processor with an integrated low-power motion-tracking chip.

Last year, Apple ran out of its initial online stock of the iPhone 5 in less than an hour, with new buyers facing a two-week ship time. That quickly ramped up to three to four weeks, with many new buyers turning to Apple's retail stores or carrier partners to get a phone sooner. It then took the company another two months before it was able to shorten the waiting times in early November, just ahead of what turned out to be a busy holiday quarter.

This launch could be Apple's biggest yet. First, it's putting two new iPhone models on sale for the first time. Second, both are being released in 11 countries simultaneously on September 20, with a wider release in other regions to follow.

To put any expectations in perspective, last year's iPhone 5 tallied up 2 million preorders in the first 24 hours. Apple went on to sell more than 5 million iPhone 5 units in the phone's first three days on sale. The year before, more than a million people preordered an iPhone 4S in the first 24 hours, which went on to become around 4 million on its opening sales weekend.

The record for the iPhone 5 was not without hiccups. Online stores experienced performance and availability issues almost immediately after opening up for sales. Both Apple and AT&T's online stores temporarily went down for maintenance, while Sprint experienced slowdowns the first half hour the phone was on sale. Similar issues plagued some International carrier partners, including T-Mobile in Germany, as well as Orange in the UK.

Along with the new iPhones, Apple is introducing a handful of new accessories, including color cases.

This story was updated several times as the preorder process progressed on Friday and to correct the starting price of the iPhone 5S.

Apple started selling its lower-end new smartphone, the iPhone 5C, with an expected delivery date of September 20. That's the day the phone will be available in stores.
screenshot by Stephen Shankland/CNET
Adding new colors -- five options for the of iPhone 5C -- makes things more complicated for online sales sites such as Verizon's.
screenshot by Stephen Shankland/CNET